This invention relates generally to apparatus useful in the fabrication of building trusses, particularly combination wood-metal floor trusses of the type comprising a pair of spaced-apart wood chord members (e.g., 2.times.4's) interconnected by a series of V-shaped metal web members, such as those shown and described in coassigned pending U.S. patent application Ser. No. 63,791.
The substitution of wood-metal floor trusses for solid lumber floor and ceiling joists has become widespread for several reasons, one being the relatively high cost of wood joists. Moreover, a combination wood-metal truss is lighter, stronger and enables duct work, piping and wiring to be routed through the truss in the open spaces between the chord members. However, several problems have arisen in the fabrication of wood-metal trusses. One problem involves the centering of the teeth struck from the V-shaped metal webs on the faces of the wood chord members so as to ensure that when the web and chord members are pressed together the maximum number of teeth are embedded in the chord members for maximum truss strength. In this regard, 2.times.4's are typically used as the wood chord members, with the teeth of the web members being pressed into the narrow faces of the 2.times.4's. However, centering the teeth on these relatively narrow faces is especially difficult to accomplish for at least two reasons. First, the thickness of the wood members may vary from member to member. For example, the thickness of one piece of timber may be 1-7/16 in. while another may be 11/2 in. or 1-9/16 in. thick (the thickness of a standard 2.times.4 is 11/2 in.). Moreover, despite the differences in thickness of the wood chord members, the outside dimension (i.e., depth) of the truss must be held within a relatively close tolerance (e.g., 1/16 in.) which is generally less than the cumulative tolerances of the wood chord members.
Another problem presented by prior apparatus for fabricating metal-wood trusses has been the relative difficulty of changing over from the fabrication of trusses of one size to the fabrication of trusses of a different size. This change-over has heretofore required substantial amounts of time and labor with consequent economic losses to the owner. Loading wood chord members into prior fabricating apparatus has also presented a problem, as has the removal of the finished truss from the apparatus.